Freescale enhanced Direct Memory Access(eDMA) Controller
The eDMA channels have multiplex capability by programmble memory-mapped
registers. channels are split into two groups, called DMAMUX0 and DMAMUX1,
specific DMA request source can only be multiplexed by any channel of certain
group, DMAMUX0 or DMAMUX1, but not both.eDMA Controller
Required properties:
- compatible :
- “fsl,vf610-edma” for eDMA used similar to that on Vybrid vf610 SoC
- reg : Specifies base physical address(s) and size of the eDMA registers.
The 1st region is eDMA control register’s address and size.
The 2nd and the 3rd regions are programmable channel multiplexing
control register’s address and size. - interrupts : A list of interrupt-specifiers, one for each entry in
interrupt-names. - interrupt-names : Should contain:
“edma-tx” - the transmission interrupt
“edma-err” - the error interrupt - #dma-cells : Must be <2>.
The 1st cell specifies the DMAMUX(0 for DMAMUX0 and 1 for DMAMUX1).
Specific request source can only be multiplexed by specific channels
group called DMAMUX.
The 2nd cell specifies the request source(slot) ID.
See the SoC’s reference manual for all the supported request sources. - dma-channels : Number of channels supported by the controller
- clock-names : A list of channel group clock names. Should contain:
“dmamux0” - clock name of mux0 group
“dmamux1” - clock name of mux1 group - clocks : A list of phandle and clock-specifier pairs, one for each entry in
clock-names.
Optional properties:
- big-endian: If present registers and hardware scatter/gather descriptors
of the eDMA are implemented in big endian mode, otherwise in little
mode.
Examples:
edma0: dma-controller@40018000 {
#dma-cells = <2>;
compatible = “fsl,vf610-edma”;
reg = <0x40018000 0x2000>,
<0x40024000 0x1000>,
<0x40025000 0x1000>;
interrupts = <0 8 IRQ_TYPE_LEVEL_HIGH>,
<0 9 IRQ_TYPE_LEVEL_HIGH>;
interrupt-names = “edma-tx”, “edma-err”;
dma-channels = <32>;
clock-names = “dmamux0”, “dmamux1”;
clocks = <&clks VF610_CLK_DMAMUX0>,
<&clks VF610_CLK_DMAMUX1>;
};
- DMA clients
DMA client drivers that uses the DMA function must use the format described
in the dma.txt file, using a two-cell specifier for each channel: the 1st
specifies the channel group(DMAMUX) in which this request can be multiplexed,
and the 2nd specifies the request source.
Examples:
sai2: sai@40031000 {
compatible = “fsl,vf610-sai”;
reg = <0x40031000 0x1000>;
interrupts = <0 86 IRQ_TYPE_LEVEL_HIGH>;
clock-names = “sai”;
clocks = <&clks VF610_CLK_SAI2>;
dma-names = “tx”, “rx”;
dmas = <&edma0 0 21>,
<&edma0 0 20>;
};
